In a statement released Wednesday, Hy-Vee said it recently detected unauthorized activity on these specific payment processing systems, which triggered the investigation with the help of leading cybersecurity firms.

No dates during which data may have been compromised nor specific affected locations were listed in the company statement, which noted "the investigation is in its earliest stages."

Hy-Vee officials said in the statement that they believe they have taken the appropriate actions to stop any unauthorized activity on the payment processing systems, have notified federal law enforcement and the payment card networks involved.